Process for waterproofing leather at low pH-values and leathers manufactured thereby

ABSTRACT

The present invention relates to a process for waterproofing leathers, furs and other fibrous materials wherein waterproofing is carried out with conventional water repellents in the presence of dispersing or stabilizing auxiliary agents at pH-values of 3.5 to 5. Alkoxy-groups-containing copolymers, synthetic or natural fatliquors and/or synthetic retanning agents (syntans) are preferably used as dispersing or stabilizing auxiliary agents.

TITLE OF THE INVENTION

This application is a 371 of PCT/EP/96/01851 filed May 3, 1996.

BACKGROUND OF THE INVENTION Field of the Invention

A process for waterproofing leather at low pH-values and leathersmanufactured thereby

The present invention relates to a process for waterproofing leathers,furs, and other fibrous materials wherein the use of dispersing orstabilizing auxiliary agents with the water repellent renders thepreviously usual, but undesirable high pH-values no longer necessary toachieve a good water repellent action.

Description of the Background

Except for some special cases where water repellents are subsequentlyapplied on the ready-made leather, hydrophobing is carried out from theaqueous float today. The water repellent effect can either be achievedby coating the fibrils and fibers of the leathers with hydrophobiccompounds or it may be based on an incorporation of special emulsifierscapable of forming stable water-in-oil emulsions. As soon as water ormoisture reaches or penetrates the leather, a water-in-oil emulsion isformed within the fiber interstices. The resultant swelling seals theleather. The structure and action of different kinds of auxiliary agentsused for waterproofing is described by R. Nowak in "Leder- undHautemarkt", 29 (1977), number 24.

Most of the water repellents used today are those responding to both ofthe above-mentioned mechanisms. Inversion makes it possible to convertproducts belonging to the class of substances forming water-in-oilemulsions into those forming oil-in-water emulsions. This may beeffected by adding certain emulsifiers, changing the pH, by fixationwith metallic salts, and other measures. Oil-in-water emulsions may beused in fatliquoring because of their optional dilutability with water.The water repellents used in practice belong to this type.

To achieve a good waterproofing effect, the water repellent mustcompletely penetrate the leather cross section (Hodder, J. J.,"Waterproof Leather Technologies and Processes", Waterproof Symposium onthe occasion of the ALCA meeting, Pocono Manors, USA, 1994, publicationin JALCA in preparation). A great handicap of the water repellents usedso far lies in the fact that their oil-in-water emulsions tend to breakat acid pH-values starting at about 5. Greasying on the grain and fleshside results, increasing in complete, mayonnaise-like precipitation ofthe product. The broken emulsion has an absolutely different emulsion orsolution behavior which is likely to become apparent in the describedprecipitation, for example. The mayonnaise-like fatty substance can nolonger penetrate the leather in fine or superfine dispersion topenetrate it uniformly. As a consequence the waterproofing effectbecomes worse.

For this reason it has become common practice to set a pH-valuepreventing early emulsion breakdown, both in the float from which thewater repellent or its oil-in-water emulsion is applied on the leatherand in the leather. In this connection, neutralization has been ofparticular importance. Leather highly neutralized throughout the crosssection, with a pH-value avoiding emulsion breakdown in all areas hasbeen necessary to ensure penetration; in practice requiring a pH of 5and above.

According to Friese et al. (Friese, H.-H., H. Constabel, W. Prinz,"Oberleder mit verbessertem Verhalten gegenuber Wasser",Leder-/Haute-Markt 35 , number 20, 1-3, 1983) neutralization to apH-value of 5.5 in the leather cross section and 6.1 in the float waseffected to make impregnated leathers of wet blue and a shaved substanceof 2.2 mm. Uniform neutralization throughout the cross section isimportant in this context. Fatliquoring (here, the water repellenttreatment carried out in the process step of fatliquoring) should becarried out at a minimum pH of 6.5 and at a highest possible temperaturein order to achieve thorough "fatliquoring". If the leather had aninsufficiently high pH-value across the whole cross section, but wasmore acidic in the middle, early breaking of the emulsion with reducedwater equivalents could occur. The more acid central layer resulted in akind of capillary action, causing an excessive water absorbency; in theBally penetrometer (Lange, J., "Qualitatsbeurteilung von Leder,Lederfehier, Lederlagerung und Lederpflege", vol. 10 of "Bibliothek desLeders", Umschau Verlag 1982, pp. 119-123, and "Bestimmung desVerhaltens gegenuber Wasser bei dynamischer Beanspruchung imPenetrometer", DIN 53 338, April 1976) or in the Maeser testingapparatus ("Dynamic Water Resistance of Shoe Upper Leather by the MaeserWater Penetration Tester", ASTM D 2099-70, and Lange, J.,"Qualitatsbeurteilung von Leder, Lederfehier, Lederlagerung undLederpflege", vol. 10 of "Bibliothek des Leders", Umschau Verlag 1982,p. 124).

The two above-mentioned test methods to determine the hydrophobicproperty of leather are dynamic ones, i.e., the water absorption isdetermined under constant bending or compressive stress of the leathersamples. The indication of the compression amplitude, the period up towater penetration, and the water absorption within certain timeintervals according to the Bally-Penetrometer-Testing permit a soundassessment for the use-value of a water repellent leather finish. As aresult of increased demands on satisfactory waterproofing, Bally testvalues with an amplitude of the leather of 7.5% are out-of-date.According to today's standards set points demanding an amplitude of 10%to 15% must be met, wherein the test periods amount to between 6 and 24hours and the water absorption is required to be below 20%. With regardto "Maeser-Flexes" a value of at least 15,000 must be achieved for goodwaterproofing.

In DE 35 29 869 A1, Bay et al. describe a process for waterproofingleathers and furs which operates in a simple method under avoidance oforganic solvents using silicone oil emulsions stabilized withN-acylamino acids (dimethylpolysiloxanes, page 3, line 41) at pH-valuesof 4.5-8, preferably 4.8-5.5. The embodiment examples A-E are carriedout in the pH range of 5-6. According to page 4, lines 3-6, however,waterproofing is insufficient since a clear improvement can only beachieved by additionally using conventional water repellents of the typeparaffin or wax emulsions.

Bay (Bay, H., "Ein Beitrag zur Hydrophobierung verschiedener Lederartenmit hoheren Anspruchen an die Wasserresistenz der Leder", Leder &Haute-Markt, 38, (1986) 24, Aug. 29, 1986, 77-79) describes as atop-waterproofing for highly waterproofed leathers the use of a purelyaqueous emulsion of special silicone oils (Densodrin®S, BASF, TechnicalInformation May 1988) according to the above-mentioned DE 35 29 869 A1,after the basic water repellent treatment has been carried out, forexample, with Densodrin®GF. Under "Application" in the TechnicalInformation (Densodrin®GF, BASF, Technische Information Dec. 1986) forthis product it reads as follows: "To achieve good penetration includinga water repellent effect throughout the leather cross section, acorresponding thorough deacidification is necessary, i.e., the crosssection should be brought to a pH of above 5".

According to Hodder (Hodder, J.J., "Waterproof Leather Technologies andProcesses", Waterproof Symposium on the occasion of the ALCA meeting,Pocono Manors, USA, 1994, publication in JALCA in preparation) polymericsofteners used as water repellents achieve good penetration only whenapplied in the pH-range of more than 5-6, depending on the respectivepolymer. Although a certain water repellency can be achieved at lowerpH-values, the high demands on Maeser-flexes and water absorptionrequire complete penetration which requires a relatively strong andcomplete neutralization of the chrome-tanned leather.

From the leather technological point of view the high pH-value isundesirable since it results in loose grain. To this regard Friese andPrinz (Friese, H.-H. and W. Prinz "Hydrophobierung modischer Leder",lecture held at the 35th Congress of AQEIC, 1st to 4th of May, 1986, inMurcia, Spain, published in Leder & Haute-Markt, 38 (1986) 32, Nov. 14,1986, 5-10) describe the use of sulfonated carboxylic acid esters asemulsifiers in combination with alkyl phosphates to manufacture waterrepellent fatliquoring agents for soft, modern leather types. The highemulsion stability permits waterproofing down to a pH of 4.0. It isrecommended to use an acrylate retanning agent to improve waterproofingthroughout the leather cross section, prior to acidification. The waterequivalents of the treated leathers were determined at 7.5% and 15%amplitude in the Bally penetrometer; however, very high, unacceptablewater absorptions (up to 38%) occurred. There are no results on theMaeser Tester which places higher demands on successful waterproofing.It is known from practical experience with these complex-active waterrepellents that their hydrophobing action is preferably used for the(weaker) semi-waterproofing of modern, i.e., softer to very softleathers. They are not suitable for highly waterproofed, firm leathers;this is explicitly stated in the above-mentioned publication on page 8,paragraph 3. This particularly applies to loosely structured andtherefore sensitive raw materials, for example, the Brazilian Zebu.Moreover, they are highly sensitive to water hardness so that they canonly be processed by using complexing agents.

In WO 92/1 3973, Friese and Prinz describe a fatliquoring agent forleather which is based on salts of phosphated OH-groups-containingglycerol tri-C₈₋₂₂ -fatty acid esters, and a process which uses thefatliquor in treatment floats with pH-values of below 5 and then adjuststo acid pH-values of 4.8 or less. If indicated at all, the embodimentexamples show an insufficient waterproofing of the leathers; forexample, in the Bally penetrometer water penetrates after only 240minutes, and the water absorption is at about 10% -wt. after only onehour.

SUMMARY OF THE INVENTION

Accordingly, it is the object of the present invention to provideauxiliary agents or a technology which overcomes the above-mentioneddrawbacks of the art. This in particular involves the possibility ofmanufacturing highly waterproofed leathers in a process at a lowpH-value, wherein both soft thin and rigid firm leather qualities areincluded with equal perfection. Moreover, the process is intended to beapplicable in an optimum manner, irrespective of the water hardness,and, if possible, it should allow a simplified process of leathermanufacture.

Most surprisingly, it has been found that this becomes possible by usingdispersing or stabilizing auxiliary agents in addition to the waterrepellent. The first-mentioned ones have the function of introducing thewater repellent or its emulsion into the interior of the leather to alarge extent, despite the unfavorable pH-conditions, and of ensuring agood distribution. Stabilizers increase the stability of the emulsionwhich can therefore penetrate deeper into the leather. Basically anysubstance is useful which has a good dispersive or stabilizing effectwithout having an excessive hydrophilic action. These include specialcopolymers, fatliquors, and also certain synthetic retanning agents, theso-called syntans which are characterized by their insensibility toacids and salts.

DETAILED DESCRIPTION OF THE INVENTION

In the journal "Das Leder", 33 (1982), pages 142-154 F. Schade and H.Traubel specify the structure of different syntans which, for example,may be cocondensates from a selection of the raw materialsnaphthalenesulfonic acid, 4,4'-dihydroxydiphenyl sulfone, aniline,dicyandiamide, sulfonated diarylethers, oligophenyl-sulfonic acids, andformaldehyde. Further indications as to syntans can be found, forexample, in "Ullmanns Enzyklopadie der technischen Chemie", 4th edition1978, volume 16, pages 137-144.

Syntans without remarkable hydrophilic properties can be synthesized andused according to the present invention by varying several raw materialsor their concentrations used. Syntans are used both in liquid andpowdery form, the powdery form mostly being loaded with cutting agentsfrom the manufacturing process (spray drying).

Alkoxy-groups-containing copolymers based on monomer mixtures of

a) 1-99% -wt. water-soluble, ethylenically unsaturated,acid-groups-containing monomers and/or unsaturated dicarboxylic acidanhydrides,

b) 1-50% -wt. ethylenically unsaturated, mono- or poly-alkoxylatedmonomers, and

c) 0-60% -wt. of further monomers copolymerizable with a) and b),

with the proviso that the weight percentage of a), b), and c) make up to100%, are suitable for both supporting the water repellent action andachieving good firmness and excellent fullness of the leather. Suchalkoxy-groups-containing polymers are described, for example, in thepatent documents U.S. Pat. No. 4,962,173, U.S. Pat. No. 4,872,995, U.S.Pat. No. 4,847,410, and DE 42 27 974 A1.

Suitable monomers of group a) include polymerizable, water-soluble,acid-groups-containing, ethylenically unsaturated monocarboxylic acids,their anhydrides and their salts; sulfonic acids and unsaturateddicarboxylic acids, their anhydrides and their semi-esters orsemiamides. Examples thereof include (meth)acrylic acid, (meth)allylsulfonic acid, vinylacetic acid, 2-acrylamido-2-methyl-propane sulfonicacid, vinylsulfonic acid, styrylsulfonic acid, maleic acid, maleicanhydride, fumaric acid, itaconic acid, and the semiesters andsemiamides of the above- mentioned dicarboxylic acids, the semiestersand semiamides being obtainable by reaction of the corresponding acidanhydrides with alcohols, amines, and amino alcohols. Preferred monomersare acrylic acid, methacrylic acid, maleic acid, and maleic anhydride.

The monomers of group b) may be obtained either by alkoxylation ofethylenically unsaturated, at least one hydroxy- oramino-group-containing compounds, or by reaction of the alkoxy adductsof saturated aliphatic, cycloaliphatic, aromatic alcohols, amines, orthiols with ethylenically unsaturated carboxylic acids, reactivecarboxylic acid derivatives, or allyl halides. Examples thereof includeethylene and/or propylene oxide-adducts of (meth)allyl alcohol,(meth)allyl amine, and hydroxyethyl (meth)acrylate, optionally furtherreacted with reactive saturated acid derivatives. Additional examplesinclude the reaction products of ethylene glycol, isopropyl glycol,butyl glycol, as well as nonylphenol, isotridecanol, which arepreferably capped at one end, with ethylene or propylene oxide andfurther reaction of the alkylene oxide adducts with (meth)acrylic acid,allyl chloride, or other reactive, unsaturated acid derivatives, forexample, the acid anhydrides, the acid halides, or the acid esters.Among these adducts the preferred ones are methoxypolyethylene glycol(meth)acrylates, nonylphenol polyglycol (meth)acrylates, and allylalcohols, each having 5 to 30 ethylene oxide units.

All monomers which are copolymerizable with a) and b) may be used asmonomers of groups c). They are used to modify the polymers further andthus permit an optimum adjustment to the water repellents to be usedaccording to the present invention. For this reason the monomersaccording to c) may have both a hydrophilic and a hydrophobic character.Examples include (meth) acryl-amide, dimethylaminopropyl(meth)acrylamide, (meth)acrylonitrile, (meth)acrylic-acid ester,hydroxyethyl (meth)acrylate, N-vinyl pyrrolidone, N-vinyl imidazole,N-vinyl acetamide, vinyl acetate, vinyl propionate, versatic acid vinylester, styrene.

The polymers are produced by bulk, solution or emulsion polymerizationunder conditions for these polymerization methods with respect toselection of the reactors, solvents, polymerization temperatures,initiators, regulators, stabilizers, and further usual polymerizationaids, which are known to the skilled artisan.

The number-average molecular weight of the polymers is in the range of500 to 100,000 g/mol, a preferred molecular weight ranges between 500and 50,000 g/mol, and particularly preferred between 500 and 20,000g/mol. The copolymers are preferably used in dissolved or emulsifiedform.

Owing to possible foam formation in the presence of furthersurface-active substances, in particular of synthetic retanning agents(syntans), they are preferably used after neutralization or also duringretannage. The copolymers may be applied prior to or simultaneously withthe water repellent.

Among the fatliquoring agents to be used according to the presentinvention in particular the synthetic products based on sulfochlorinatedparaffins or chloroparaffins provide a deep thorough fatliquoring shownin a dry surface. Although these types of fatliquors, because of thechemical structure, are said to have a wetting effect on leathers andthus reduce the water repellent action, good waterproofing values havesurprisingly been achieved. It seems that the hydrophilic character isovercompensated by the stabilization of the water repellent. (Stronglydispersing syntans show a similar behavior, provided that they do nothave extreme hydrophilic properties). In addition to syntheticfatliquors, those based on natural raw materials may also be used in theprocess according to the present invention. These include both the fattysubstances of animal origin, such as fish oil, whale oil, neatsfoot oil,tallow, and vegetable oils, such as those obtained from cottonseed,castor, sunflowers, peanuts, or olives. The water-miscible products areoften modified by hydrophilic sulfonic groups. They are obtained bysulfation, sulfitation, or formation of sulfonic acids. The use of amixture of different synthetic and natural fatliquors in the processaccording to the present invention proved to be advantageous. Syntheticfatliquors based on copolymers may also be used according to the presentinvention; however, they must have a sufficient stabilizing action atpH-values of 5 or less in this case too.

In addition to the advantageous operating method at reduced pH, the useof the dispersing or stabilizing products according to the presentinvention permits employment of the major water repellent portionalready in neutralization/retannage so that simplified formulations maybe obtained. The leather's absorption capacity for the water repellentis higher in the early neutralization/retannage state than at a laterstage, during "actual" waterproofing. So-called compact operations arethereby favored or made possible at all; they reduce the processingsteps (base fatliquoring--base waterproofing--top-waterproofing) inleather manufacturing. However, the greatest advantage is thepossibility of avoiding exposure of sensitive raw materials to a high pHwhich involves deliberate provocation of an inferior quality.

Despite the low pH-values of the working floats of the process accordingto the present invention, which are in the range of 3.5 to 5, preferablyof 4-5, and particularly preferred between 4.3-4.7, there are noprecipitations including resultant greasying. Usually, the leathersurface is dry, and the leathers have an excellent waterproof behavior.Depending on the leather thickness, processing time, and tannage thepH-value in the leather may be 0.2 to 0.3 pH-units lower than that ofthe float.

The amounts of dispersing auxiliary agent used range between 2-10% andpreferably between 2-5%, relative to the shaved weight of the usedwet-blue material or to the wet weight of the furs.

The subject matter of the present invention also includes leathers,furs, and other fibrous materials which have been rendered waterproofaccording to the process of the present invention.

The following embodiment examples will illustrate the present inventionin greater detail. It is shown that the leathers may be waterproofedboth in multistage and compact processing (direct method) according tothe process of present invention. The excellent hydrophobic propertiesof the leathers are shown by measurements with the Bally-Penetrometer orwith the Maeser-Test.

EXAMPLE 1

a) Production of the used alkoxy-groups-containing copolymer 325 gdeionized water, 138 g acrylic acid, 10 g dodecylbenzene sulfonic acid,12 g nonylphenoxy-(14 EO)methacrylate, 0.2 g mercaptoethanol, and 1 g ofa 0.6% iron(II)-sulfate solution are placed in a three-neck glass flaskequipped with stirrer and condenser. Polymerization is started at 20° C.by simultaneous addition of a solution of 3.6 g sodium persulfate in 10g water and 1.8 g sodium bisulfite in 10 g water. A temperature maximumof 99° C. is reached within 5 minutes. The reaction is continued at 80°C. for two hours. After 30 and after 90 minutes, 1.8 g and 1 g of theperoxo compound in 7 g water are added for secondary catalysis. After atotal reaction time of two hours, 27.3 g butyl diglycol is added, andthe mixture is neutralized by adding 104.3 g of a 25% ammonia solution.A finely-dispersed, flowable emulsion with 30% active substance isobtained which may be diluted with water at will.

Viscosity (Brookfield RVM, Sp. 6, 10 rpm): 19,000 mPas, pH-value (1:10):6.4.

b) Application in Leather Technology

Shoe upper leather, waterproofed, white

    __________________________________________________________________________    Material: chrome-tanned, South American Zebu-skins                            Shaved substance:                                                                       2.0-2.2 mm                                                          Percentages relate to shaved weight                                           WASHING:  300.0%                                                                            water 30° C.                                                       0.5%                                                                              oxalic acid  )                                                            2.0%                                                                              synth. white )           20 min.                                              tanning agent                                                   Drain off bath                                                                NEUTRALIZATION:                                                                         100.0%                                                                            water 35° C.                                                       2.5%                                                                              sodium acetate     undissolved                                                                         90 min.                                              pH: 4.4-4.5                                                     Drain off bath                                                                              (cross section evenly neutral-                                                ized throughout)                                                WASHING:  300.0%                                                                            water 35° C.       5 min.                                Drain off bath                                                                RETANNING/                                                                              100.0%                                                                            water 35° C.                                             WATERPROOFING:                                                                          4.0%                                                                              copolymer acc. a)  1:5   20 min.                                          +6.0%                                                                             water repellent    1:4 in 60° C.                                                                60 min.                                          +6.0%                                                                             synth. white tan-                                                                          )                                                                ning agent                                                                4.0%                                                                              polymer tan. agent                                                                         )           45 min.                                              with softening and                                                                         )                                                                filling action                                                                             )                                                                pH: 4.6-4.7                                                               +0.5%                                                                             formic acid        1:5   20 min.                                Drain off bath                                                                              pH: 4.1                                                         WATERPROOFiNG:                                                                          100.0%                                                                            water 55° C.                                                       0.5%                                                                              copolymer acc. a)  1:5   10 min.                                          2.0%                                                                              water repellent    1:4 in 60° C.                                                                45 min.                                Drain off bath                                                                WASHING:  300.0%                                                                            water 20° C.                                                       1.0%                                                                              formic acid        1:5   10 min.                                Drain off bath                                                                FIXATION: 100.0%                                                                            water 25° C.                                                       0.5%                                                                              formic acid        1:5   10 min.                                              pH: 3.2                                                                   +2.5%                                                                             zirconium tanning ag.                                                                            undissolved                                                                         60 min.                                Drain off bath                                                                2× WASHING:                                                                       300.0%                                                                            water 25° C.      10 min.                                __________________________________________________________________________

Leather horse-up overnight, setting out, vacuum drying (3 min./65° C.),suspension drying, conditioning, staking, air-off (vacuum 30 sec./65°C.).

In the Bally penetrometer at 10% amplitude the leather showed waterpenetration after >420 minutes at a water absorption of 11%.

EXAMPLE 2

Upper leather, waterproofed. dyed

    __________________________________________________________________________    Material: chrome-tanned, South American Zebu-skins                            Shaved substance:                                                                       1.8-2.0 mm                                                          Percentages, relative to shaved weight                                        WASHING:  300.0%                                                                            water 35° C.                                                       0.3%                                                                              oxalic acid       15 min.                                       Drain off bath                                                                RETANNING:                                                                              100.0%                                                                            water 45° C.                                                       1.0%                                                                              chrome sulfate 25/33                                                                      undis.                                                                              10 min.                                                 2.0%                                                                              chrome-containg.,                                                                       )                                                                   highly exhausting                                                                       )                                                                   synth. retan. agent                                                                     ) undis.                                                                              60 min.                                                 1.0%                                                                              sodium formate                                                                          )                                                     Drain off bath                                                                              pH: 4.0                                                         NEUTRALIZING/                                                                           100.0%                                                                            water 35° C.                                             RETANNING/                                                                              1.0%                                                                              sodium formate                                                                          )                                                     WATERPROOFING:                                                                          3.0%                                                                              neutralizing synth.                                                                     )                                                                   aux. tannin                                                                             )       60 min.                                                     pH: 4.5                                                                       (Leather cross section                                                        through-neutralized)                                                      +3.0%                                                                             copolymer acc. to                                                             Example 1a) 1:5   20 min.                                                 +6.0%                                                                             water repellent                                                                           1:4 in 60° C.                                                                45 min.                                                 +4.0%                                                                             neutralizing synth.                                                                     )                                                                   auxiliary tannin                                                                        )       90 min.                                                 5.0%                                                                              chestnut extract,                                                                       )                                                                   powder    )                                                               3.0%                                                                              dye       )                                                               +0.3%                                                                             formic acid                                                                             ) 1:5   20 min.                                       Drain off bath                                                                              pH: 3.9-4.0                                                     WASHING:  300.0%                                                                            water 45° C.                                                                             10 min.                                       Drain off bath                                                                WATERPROOFING:                                                                          100.0%                                                                            water 45° C.                                                       0.1%                                                                              ammonia     1:5    5 min.                                                 +1.0%                                                                             copolymer acc. to                                                             Exampe 1a)  1:5   10 min.                                                 +4.0%                                                                             water repellent                                                                           1:4 in 60° C.                                                                60 min.                                                 +0.5%                                                                             formic acid 1:5   20 min.                                       Drain off bath                                                                              pH: 4.0                                                         FIXATION: 100.0%                                                                            water 40° C.                                                       3.0%                                                                              commercial self-                                                              basifying chrome                                                              tan. agent  undis.                                                                              90 min.                                       Drain off bath                                                                2× WASHING:                                                                       300.0%                                                                            water 25° C.                                                                             10 min. each                                  __________________________________________________________________________

Leather horse-up overnight, setting out, vacuum drying (3 min./80° C.),suspension drying, conditioning, staking, air-off (vacuum 30 sec./75°C.).

In the Bally-Penetrometer at 10% amplitude the leather showed waterpenetration after >420 minutes at a water absorption of 9%.

Maeser Test: Number of flexes >165,000/>165,000 Water absorption % 14110

EXAMPLE 3 (Compact Processing)

Cattle upper leather. nubuck. waterproofed

Direct method

    __________________________________________________________________________    Material:                                                                             chrome-tanned US-cattle hides                                         Shaved substance:                                                                     1.8 mm                                                                Percentages, relative to shaved weight                                        Retanning/Waterproofing/Dyeing in same bath                                           100.0%                                                                            water 35° C.                                                       6.0%                                                                              neutralizing aux. 60 min.                                                     tannin                                                                        pH: 4.6                                                                   +3.0%                                                                             copolymer acc.                                                                to Ex. 1a)  1:5   10 min.                                                 3.0%                                                                              dye       )                                                               0.3%                                                                              sodium bicar-                                                                           )                                                                   bonate    ) undis.                                                                              10 min.                                                 +8.0%                                                                             wat repellent                                                                             1:4 in 60° C.                                                                45 min.                                                 +8.0%                                                                             synth/veget.                                                                  mixed tann. agent 60 min.                                                 +1.0%                                                                             formic acid 1:5   2 × 20 min.                                           pH: 3.8                                                                   +3.0%                                                                             chrome sulfate 25/33                                                                            90 min.                                                 +1.0%                                                                             dye               15 min.                                                 +0.5%                                                                             formic acid       20 min.                                         Drain off bath                                                                            pH: 3.5                                                           WASHING:                                                                              200.0%                                                                            water 50° C.                                                                             10 min.                                         __________________________________________________________________________

Leather horse-up overnight, setting out, vacuum drying (3 min./80° C.),suspension drying, conditioning, staking, buffing 220/280.

In the Bally-Penetrometer at 10% amplitude the leather showed waterpenetration after >420 minutes at a water absorption of 9%.

EXAMPLE 4

Cattle upper leather, nubuck, waterproofed

Direct operation

    __________________________________________________________________________    Material: chrome-tanned, European cattle hides                                Shaved substance:                                                                       1.8-2.0 mm                                                          Percentages relate to shaved weight                                           WASHING:  300.0%                                                                            water 35° C.                                                       +0.3%                                                                             oxalic acid       20 min.                                       Drain off bath                                                                WASHING:  200.0%                                                                            water 35° C.                                                                             10 min.                                       Drain off bath                                                                RETANNING:                                                                              150.0%                                                                            water 35° C.                                                       +4.0%                                                                             chrome syntan     40 min.                                                 +2.0%                                                                             sodium formate                                                                          )                                                               5.0%                                                                              neutralizing                                                                            )       60 min.                                                     aux. tannin                                                                             )                                                     Drain off bath                                                                              pH: 4.6                                                         WATERPROOFING/                                                                          150.0%                                                                            water 45° C.                                             RETANNING/                                                                              +2.0%                                                                             copolymer acc.                                                                            1:5   20 min.                                       DYEING:       to Ex. 1a)                                                                +5.0%                                                                             water repellent                                                                         )                                                               5.0%                                                                              polym. softener                                                                         ) 1:4 in 60° C.                                                                90 min.                                                 +8.0%                                                                             synth/veget.                                                                            )                                                                   mixed tann. ag.                                                                         )       60 min.                                                 3.0%                                                                              dye       )                                                               +4.0%                                                                             amphot. copoly.   40 min.                                                 +1.5%                                                                             formic acid 1:5   2 × a 20 min.                           Drain off bath                                                                              pH: 3.8                                                         TOP-WATER-                                                                              200.0%                                                                            water 50° C.                                             PROOFING: +0.2%                                                                             ammonia            5 min.                                                 +1.0%                                                                             copolymer acc.                                                                            1:5   10 min.                                                     to Ex. 1a)                                                                +2.0%                                                                             water repellent                                                                           1:4 in 60° C.                                                                40 min.                                                 +0.7%                                                                             formic acid       20 min.                                       Drain off bath                                                                              pH: 3.7-3.8                                                     FIXATION: 150.0%                                                                            water 35° C.                                                       3.0%                                                                              chrome sulfate 25/33                                                                            90 min.                                       Drain off bath                                                                              pH: 3.8                                                         WASHING:  200.0%                                                                            water 50° C.                                                                             10 min.                                       __________________________________________________________________________

Leather horse-up overnight, setting out, vacuum drying (3 min./80° C.),suspension drying, conditioning, staking, buffing 220/280.

In the Bally penetrometer at 10% amplitude the leather showed waterpenetration after >420 minutes at a water absorption of 13%.

    ______________________________________                                        Maeser Test:                                                                              Number of flexes                                                                             >45,000/>45,000                                                Water absorption %                                                                           11/12                                              ______________________________________                                    

We claim:
 1. A process for waterproofing leathers, furs, and otherfibrous materials, comprisingcontacting a fibrous material in a float ata pH of 3.5 to 5 with a dispersing or stabilizing auxiliary agentcomprising an alkoxy-containing copolymer having a molecular weight of500 to 100,000 consisting of the following monomer units (α) 1-99% -wt.of water soluble, ethylenically unsaturated, acid group-containingmonomers and/or unsaturated dicarboxylic acid anhydrides and/or theirsalts, (β) 1-50% -wt. of ethylenically unsaturated, mono- orpolyalkoxylated monomers, and (γ) 0-60% -wt. of additional monomerscopolymerizable with (α) and (β), with the proviso that the weightpercentage of (α), (β), and (γ) make up to 100%, where thealkoxy-containing copolymer consists of elements selected from C, H, O,N and S; and contacting the fibrous material in the float with a waterrepellent.
 2. The process according to claim 1, wherein the dispersingor stabilizing auxiliary agent further comprises sulfochlorinatedparaffins or chloroparaffins.
 3. The process according to claim 1,wherein the dispersing or stabilizing auxiliary agent is mixed with thewater repellent and used together.
 4. The process according to claim 1,wherein the dispersing or stabilizing auxiliary agent is used in aneutralization/retannage step.
 5. The process according to claim 1,wherein a major portion of the water repellent is used during aneutralization/retannage step.
 6. The process according to claim 1,wherein the dispersing or stabilizing auxiliary agent is contacted withthe fibrous material at a pH from 4.0 to 5.0.
 7. The process accordingto claim 1, wherein the dispersing or stabilizing auxiliary agent iscontacted with the fibrous material at a pH from 4.3 to 4.7.
 8. Theprocess according to claim 1, wherein the dispersing or stabilizingauxiliary agent is used in an amount of 2 to 10% -wt. relative to ashaved weight of the fibrous material.
 9. The water-proofed fibrousmaterial obtained by the process of claim
 1. 10. The water-proofedfibrous material of claim 9, which is a leather or a fur.
 11. A processfor waterproofing leathers, furs, and other fibrous materials,comprisingcontacting a fibrous material at a pH of 3.5 to 5 with adispersing or stabilizing auxiliary agent comprising analkoxy-containing copolymer having a molecular weight of 500 to 100,000consisting of the following monomer units(α) 1-99% -wt. of watersoluble, ethylenically unsaturated, acid group-containing monomersand/or unsaturated dicarboxylic acid anhydrides and/or their salts, (β)1-50% -wt. of ethylenically unsaturated, mono- or polyalkoxylatedmonomers, and (γ) 0-60% -wt. of additional monomers copolymerizable with(α) and (β), with the proviso that the weight percentage of (α), (β),and (γ) make up to 100%, where the alkoxy-containing copolymer consistsof elements selected from C, H, O, N and S; and contacting the fibrousmaterial with a water repellent, wherein the dispersing or stabilizingauxiliary agent is mixed with the water repellent and used together. 12.The process according to claim 11, wherein the dispersing or stabilizingauxiliary agent further comprises sulfochiorinated paraffins orchloroparaffins.
 13. The process according to claim 11, wherein thedispersing or stabilizing auxiliary agent is used in aneutralization/retannage step.
 14. The process according to claim 11,wherein a major portion of the water repellent is used during aneutralization/retannage step.
 15. The process according to claim 11,wherein the dispersing or stabilizing auxiliary agent is contacted withthe fibrous material at a pH from 4.0 to 5.0.
 16. The process accordingto claim 11, wherein the dispersing or stabilizing auxiliary agent iscontacted with the fibrous material at a pH from 4.3 to 4.7.
 17. Theprocess according to claim 11, wherein the dispersing or stabilizingauxiliary agent is used in an amount of 2 to 10% -wt. relative to ashaved weight of the fibrous material.
 18. A water-proofed fibrousmaterial obtained by the process of claim
 11. 19. The water-proofedfibrous material of claim 18 which is a leather or a fur.
 20. A processfor waterp roofing leathers, furs, and other fibrous materials,comprisingcontacting a fibrous material in a float at a pH of 3.5 to 5with a dispersing or stabilizing auxiliary agent comprising analkoxy-containing copolymer having a molecular weight of 500 to 100,000consisting of the following monomer units(α) 1-99% -wt. of watersoluble, ethylenically unsaturated, acid group-containing monomersand/or unsaturated dicarboxylic acid anhydrides, the acidgroup-containing monomers and dicarboxylic acid anhydrides beingselected from the group consisting of acrylic acid, (meth)acrylic acid,(meth)allyl sulfonic acid, vinylacetic acid,2-acrylamido-2-methyl-propane sulfonic acid, vinylsulfonic acid,styrysulfonic acid, maleic acid, maleic anhydride, flmaric acid,itaconic acid, and the semiesters and semi,des of maleic acid, fimaricacid and itaconic acid, (β) 1-50% -wt. of ethylenically unsaturated,mono- or polyalkoxylated monomers selected from the group consisting ofmethoxypolyethylene glycol (meth)acrylate, nonylphenol polyglycol(meth)acrylate, ethylene and/or propylene oxide-adducts of (meth)allylalcohol, (meth)allyl amine, and hydroxyethyl (meth)acrylate, andreaction products of at least one of ethylene glycol, isopropyl glycol,butyl glycol, nonylphenol and isotridecanol with ethylene or propyleneoxide, and (γ) 0-60% -wt. of additional monomers copolymerizable with(α) and (β) selected from the group consisting of (meth)acrylamide,dimethylaminopropyl (meth)acrylamide, (meth)acrylonitrile, hydroxyethyl(meth)acrylate, N-vinylpyrrolidone, N-vinyl imidazole, N-vinylacetamide, vinyl acetate, vinyl propionate, versatic acid vinyl ester,and styrene, with the proviso that the weight percentage of (α), (β),and (γ) make up to 100%; and contacting the fibrous material in thefloat with a water repellent.